A Veterans Affairs Department official said Wednesday the department is investigating allegations of a secret waiting list for medical appointments at the Phoenix VA Health Care System but, so far, has found no evidence that such a list exists.

Responding to concerns posed by lawmakers at a Senate Veterans Affairs Committee hearing, VA Undersecretary for Health Dr. Robert Petzel said a thorough investigation is underway by the VA’s Office of Inspector General.

“We do care very deeply about about our veterans. ... We take these allegations very seriously,” Petzel said.

CNN reported last week that a former physician from the Phoenix facility provided documents and emails showing that local VA leaders reported false wait times for patients to higher officials in order to fake progress in getting veterans timely care.

According to the report, a second, private wait list included thousands of veterans who waited months or years for appointments, with as many as 40 patients dying while waiting for care.

Committee Chairman Sen. Bernie Sanders, I-Vt., promised an “objective investigation” into the issue as well as hearings to uncover the truth.

Senators expressed concerns about the independence of the VA OIG and the speed of its investigations. Sen. Richard Blumenthal, D-Conn., recommended that the committee proceed with its own investigation rather than wait for the outcome of the VA OIG.

The allegations are not the first to raise questions about the VA’s management of patient care and appointments. Earlier this month, VA officials acknowledged that delays in cancer treatment consultations may have played a role in the deaths of 23 veterans and compromised the health of 53 others.

Petzel said the VA inspector general has not shared the time frame for completing its investigation into the Phoenix charges. He added that the central office’s look at the allegations has not found “any evidence to date that anyone died while on the waiting list.”